Escalating violence and a vicious cycle of retaliation could leave Syria ungovernable even if a winner finally emerges from President Bashar al-Assad's battle with rebels. Nearly a year and a half since the uprising erupted, initially as peaceful protests for reform, Assad's forces and their insurgent foes are fighting a messy conflict with no frontline and scant regard for the rules of war. Assad has deployed air strikes and artillery to pound restive towns into submission, hitting civilian homes and hospitals. Rights groups say his forces have committed massacres. Rebels have shot or slit the throats of captured Assad supporters and hurled corpses off high buildings. – Reuters